The present invention is directed to tube couplings, and more particularly, to tube couplings and coupling elements which prevent relative rotation between tubular coupling members.
Tube couplings of the type in the present invention are generally shown and described in U.S. Pat. Nos. 3,521,910 and 5,145,219, herein incorporated herein by reference. Those patents describe tube couplings wherein first and second tubular members having central through passages and sealing end faces with annular, raised beads are arranged to sealingly engage on opposite sides of an annular metal gasket. Suitable threaded nut members are then rotated to drive the tubular members toward each other to cause the beads to sealingly engage the gasket.
U.S. Pat. No. 5,145,219 proposes modifications and/or additional components to reduce or eliminate undesired relative movement between the tubular members and between the tubular members and the gaskets. The ""219 patent is primarily directed to preventing such relative rotation due to transmitted torque forces. Transmitted torque is the rotational force applied to the tubular members during make up of the fitting. In some situations it may be desired to accommodate xe2x80x9cbreak awayxe2x80x9d torque, which is a much stronger rotational force applied to the coupling after it is made up. Break away torques may be imparted upon the system by environmental forces, as well as rough handling by operators. When the imparted forces are sufficient so as to cause one coupling member to xe2x80x9cbreak awayxe2x80x9d and rotate relative the other coupling member, or relative the sealing gasket, the gasket may be scored. Accordingly, there exists a need for a tube coupling which can prevent relative rotation between tubular members when break away torque forces are applied.
The present invention resides in various coupling and coupling components which prevent relative rotation between tubular members when break away torque forces are applied to the tubular members. In one embodiment, the invention is a locking ring for preventing relative axial rotation between two generally tubular members. The ring is shaped to receive a sealing gasket and has two side faces wherein each side face is shaped to frictionally engage one of the tubular members to thereby prevent relative axial rotation between the tubular members. The invention also includes a coupling incorporating the locking ring, and a method of making a coupling having a locking ring to prevent relative rotation between the tubular members.
In another preferred embodiment, the invention is a coupling comprising two generally tubular members each having a sealing end face, a raised, annular sealing bead, an inner bore, and a frictional surface located radially outward of the sealing bead. The tubular members are generally coaxially arranged such that the sealing faces face each other. The coupling further comprises a sealing gasket captured between the sealing beads for sealing the coupling, wherein the frictional surfaces engage the sealing gasket to prevent relative rotation between the tubular members.
Various other embodiments of the invention are described and claimed herein, and other features and advantages of the present device will become apparent from the following detailed description, with reference to the accompanying drawings and claims, which form a part of the specification.